Electronic appliances having rechargeable batteries are becoming more commonplace, particularly with respect to personal computing and communications devices, especially lap top and notebook size personal computers. These devices, as well as other devices have evolved a multiplicity of different ways in which the batteries may be charged. In most instances, and typically along with components which are supplied with the notebook or laptop computer at the time of purchase, a recharger power source is plugged into the personal computer during the time which the notebook computer contains the rechargeable batteries. The power from the recharger power source, also known as the original external power supply, is routed to the batteries as they reside in the computer. Such a scheme may be efficient with respect to the purpose of enabling operation of the personal computer even when the battery is depleted, but it is not conducive to freeing the personal computer from the charging process, nor does it help the user to keep a supply of freshly charged batteries without the problems associated with re-loading the personal computer with each successive set of batteries in order to charge those sets of batteries. Further, the computer batteries may not re-charge efficiently while the computer is being used with power from the re-charging "brick."
A further complication in an attempt to have a more efficient system is due to differing voltage requirements for different personal computers. Each personal computer system sold will usually have a different size, shape, and type of battery, having different voltage and current characteristics. Consequently, each original external power supply will have the capability of converting the 115 volt house current to a different level of direct current voltage before supplying that voltage to the notebook computer for the purpose of either running the computer, charging the computer's batteries, or both, if possible.
Further, each original external power supply is designed with limitations on the amount of power supplied, and other characteristics which may be particular to the computer's need for a "clean" or non rippling power source. In addition, the original external power supply has a mass density usually as high or higher than other components of the system; it is very heavy. When the user is traveling, it adds significant weight to luggage. In addition, when travelling, the user may not always be near a source of alternating current power. If direct current power is available, an inverter is required to convert the direct current to alternating current, which the original external power supply then converts to direct current to be utilized by the laptop computer.
Other schemes, not necessarily in the notebook computer area, have involved the placement of charging electronics directly into a battery pack. Examples of this technique include the use of flashlights plugged directly into the wall. This has two disadvantages. First, when each battery has such electronics, even if only an additional electrical connector to accommodate a power plug, the cost of each battery pack increases. Secondly, all battery packs have a limited life and will be disposed of. The presence of additional structures on the disposed of batteries equates to additional waste. Further, the imposition of additional electronics equates to an increase in space requirements. One of the competitive aspects of small personal computers is their reduced size, and this goal would be defeated if the presence of additional electronics were imposed on each battery pack.
The possibility of a separate charger for personal computer batteries, as well as other personal appliance batteries has been considered and adopted, especially in group settings where a large number of batteries need to be available and re-charged on a large scale. The use of a separate recharging stand, the so-called "drop charger," has previously carried with it many of the disadvantages associated with charging the batteries with the appliance. Each drop charger is tied to the shape and electrical characteristics of the battery to be charged, and each drop charger has its own AC to DC power conversion circuitry. Such drop chargers are typically just as heavy as the original external power supply, and also typically cost as much or more.
Some direct current power supplies which operate with standard output voltages, such as 12 volts may be obtained inexpensively due to their large numbers of manufacture. Further, a source of 12 volt power is available in a variety of other circumstances, such as automobiles, boats, and from other, stand alone power supplies. An example of the latter might be an amateur radio station where a 12 volt supply is usually readily available. In such cases, the 12 volt power supply may actually provide a cleaner, less distorted supply of power than could be made available with the original external power supply.
The electrical characteristics of a battery pack are governed by the shape of the chemical cell, and the voltage and current load demanded by the appliance. The shape of the chemical cell may also determine the charging rate, and whether a charging cycle can be employed. Such charging cycles may incorporate typically a fast, higher voltage and current charging process for a limited time, followed by a slower charge of open-ended duration. In turn, the shape and size of the battery pack is determined by the physical restraints upon the personal computer.
Under currently available configurations, the circuitry which determines the charging characteristics are incorporated with the original external power supply. The additional weight of this circuitry is required to be transported with the computer, even when no charging is desired, as when it is desired to power the computer directly from the non-portable power source.
Further, all of the above characteristics makes it difficult for a manufacturer to even attempt to build and supply a single drop charger, or charging system for a particular battery pack. A manufacturer would have to supply a custom drop charger accommodated for the original external power supply, as well as other specialized components for each portion of the battery pack charging system. Such custom designs severely limit the entry into such a market, and raise the cost to the consumer for any such products supplied. Other market limitations involve the risk of investment in inventory. For a manufacturer of drop chargers and power supplies, the cost of the inventory of customized parts, as well as the probability of obsolescence would have to be included in the price computation. The probability of obsolescence factor will always work to the disadvantage of an outside manufacturer (one who does not manufacture the appliance to which the power pack is to be connected). An inside manufacturer can control the obsolescence, and in some cases deliberately cause the obsolescence to defeat the ability of the outside manufacturer to compete. This factor, in combination with the natural marketing advantage obtainable on products whose source is the same source as the appliance (inside manufacturer), works to the disadvantage of consumers and to the denigration of competition.
What is therefore needed is an array of power transfer components which can accomplish several goals. The power transfer components should be lightweight and interconnectable. The power transfer components should be re-configurable to quickly take advantage of the power which is available. The power transfer components should be amenable to re-configuration to meet the particular demands of the notebook computer user. The system should also maximize the power availability to the user both in terms of maximizing his availability to power the computer from a non-portable source of power, as well as the ability to insure that an ample source of portable power will be available.
The components should be designed to avoid specialization to enable electrical characteristic redundancy. What is needed is a charging and power supply system which has the minimum number of parts specific to a single model of power pack, and which facilitates modularization minimizing value of the components which have the specific characteristics.
What is also needed is a recharger and power distribution system which allows a manufacturer to maximize the use of parts and system components which are common to all drop charger units manufactured. A structure enabling such use of common components and parts would help to eliminate the risk associated with multiple sets of custom parts.